1. Field of the Invention
The present invention relates generally to the field of automobile accessories, and in particular to an electromechanical power lift assembly for operating an automobile door window.
2. Description of the Prior Art
Most automobiles are provided with a manually operated, hand crank assembly for raising and lowering the door windows. In such conventional arrangements, the automobile door has interior and exterior side panels enclosing a compartment with a window mounted for reciprocal movement into and out of the compartment. A mechanical crank assembly is lodged inside the compartment and coupled intermediate the door and window with a crank stub projecting through the interior side panel for engaging a manually operable crank handle. In this arrangement, a rotary crank force applied to the crank stub is transmitted directly through a gear to a scissors jack or other assembly for extending and retracting the window.
A popular feature which is provided on an optional basis is an electrically operated power window lift assembly in which the manually operated crank apparatus is eliminated. In the conventional power window arrangement, an electrical switch is provided for applying operating power to a drive motor which is coupled directly to the scissors jack and window, with rotation of the drive motor being translated into vertical movement of the window by means of the scissors jack and a rack and gear assembly.
Field conversion of a manually operated mechanical window lift assembly to a power lift assembly having factory components is not practical because access to the interior of the welded door panel assembly is limited and because of the special tooling required for the removal and installation of welded components within the door panel. Various prior art attempts to convert a manual lift assembly into a power lift assembly have been generally unsatisfactory for the foregoing reasons and because of the difficulty of applying a rotary cranking force to the existing crank stub in an arrangement which is both efficient and aesthetically pleasing. A further problem which has limited the success of prior art arrangements is the provision of a satisfactory window travel limit control to prevent overheating the drive motor when operating power is continuously applied after the window has reached its fully extended or fully retracted position.